Title : Development of a fertility restorer for novel inap Brassica napus CMS by genetic introgression of one Chinese woad chromosome
Abstract:
The following points will be discussed • Concept and Principle of Cytoplasmic male sterility and fertility restoration • Production of novel inap Brassica napus CMS via somatic fusion with Chinese woad • Development of a restorer for inap CMS through genetic introgression • The organisations interested in CMS and Restorer • Concept and Principle of Cytoplasmic male sterility and fertility restoration Cytoplasmic male sterility (CMS) can occur either in natural plant populations by the natural mutation of mitochondrial loci (autoplasmy CMS), or as a result of crosses in which the nuclear genome of one species has been moved into the cytoplasmic background of another (known as alloplasmy CMS). Generally, the expression of CMS gene can be suppressed by special nuclear gene named as restorer of fertility (RF, or restorer) gene(s) derived from cytoplasm donor species. A CMS fertility restoration system has been widely used as an excellent pollination control system to facilitate hybrid seed production for many crops, including oilseed rape (Brassica napus L.). Though a large number of alloplasmics for Brassica crops have been produced, only Ogura-INRA B. napus CMS with the wild radish cytoplasm and Mori B. juncea CMS produced from somatic fusion with Moricandia arvensis, were successfully exploited for commercial seed production on a large scale after systematic improvement of developmental abnormalities, including leaf chlorosis. • Production of novel inap B. napus CMS via somatic fusion with Chinese woad The intertribal somatic hybrids (2n = 52, AACCII) between B. napus (2n = 38, AACC) and Isatis indigotica Fort. (Chinese woad; 2n = 14, II) of the Isatideae tribe were obtained (Du et al., 2009) and backcrossed continuously to B. napus, resulting in the development of one novel B. napus CMS with carpelloid stamens (named inap CMS) (Kang et al., 2017). • Development of a restorer for inap CMS through genetic introgression RF gene(s) for inap CMS existed in one particular woad chromosome which was carried by one fertile monosomic alien addition line (MAAL) of rapeseed. The selfed progenies of this MAAL were selected and analyzed to screen the rapeseed-type plants (2n=38) with good male fertility and produce their doubled haploid (DH) lines by microspore culture. From the investigation of fertility restoration in the F1 hybrids with inap CMS, one DH line was identified to restore the male fertility well and likely carried one dominant RF gene. This restorer produced the brown pollen grains as the woad and this MAAL did, suggesting that this trait was closely linked with RF gene(s). This restorer contained 38 chromosomes of rapesee. The successful breeding of the restorer for inap CMS rendered this new pollination control system feasible for rapeseed hybrid production, after Ogura CMS system in B. napus and Mor CMS system in B. juncea.
